无法删除使用beginCache创建的缓存项

Question

I have a fragment that I'm caching because there are a lot of database hits to generate the content.

main.php:

    'cache'=>array(
            'class'=>'system.caching.CFileCache'
    )

view.php

<?php if($this->beginCache("my_id", array('duration' => 315360000))) { ?>
   // lots of heavy stuff
<?php $this->endCache(); } ?>

My cached fragment only changes when I adjust the configuration in a database table. I'm trying to find a way to delete the cached item using the "my_id". The Yii documentation is somewhat misleading because when it talks about beginCache it refers to the key ("my_id"), but when it talks about deleting items from the cache it also talks about the key, but it is not the same key! beginCache is essentially a wrapper for an COutputCache widget and so "my_id" is not the key used in the cache.

Does anyone know how to convert "my_id" into a cache-friendly key so that I can delete that specific item from the cache.

I've tried extending from CFileCache but my key is generated from COutputCache which uses CFileCache and I don't think there is a back route. I have also tried beginning a widget with an overloaded version of COutputCache which works but just seems like a really nasty hack.

    $properties = array();
    $properties['id']=Yii::app()->params["cache_name_matrix"];
    $cache=$this->beginWidget('MyCOutputCache',$properties);
    $key = $cache->getKeyHack();

My current work around is flush the whole cache but this gets rid of everything and seems a little bit heavy handed.

Any ideas?

Answer 1

COutputCache calculates the cache key using protected method called getCacheKey which internally calls getBaseCacheKey and then depending on specified variations transforms it. In your, the simplest case, with no variations, I believe it will end up with something like 'Yii.COutputCache.my_id.......' where 'Yii.COutputCache.' is COutputCache::CACHE_KEY_PREFIX. Take a look at the code of this method.

So, knowing this, you technically can delete your fragment manually. But I strongly encourage you to take a look at mechanism of dependencies described in the manual. You said you invalidate this fragment if something changes in your database, so probably CDbCacheDependency is what you need.